Along with development of display technology, touch screen technology also develops rapidly. Touch screens, according to structure, can be divided into two types including add-on touch screens and in-cell touch screens. An in-cell touch screen, with a touch sensing electrode being embedded inside a liquid crystal display panel, can reduce a thickness of a device as a whole and reduce manufacture cost.
As illustrated in FIG. 1, an in-cell touch screen includes a color filter substrate 10 and an array substrate 20 that are disposed opposite to each other. The color filter substrate 10 includes a first base substrate 1, a plurality of color pixel areas 2 provided on the first base substrate 1, and light-block areas 3 that are located between the color pixel areas 2. Touch sensing electrodes 4 are provided at positions of the light-block areas 3. An array substrate 20 includes a second base substrate 7 and a transparent conductive layer disposed on the second base substrate 7. The transparent conductive layer includes touch driving electrodes 6 and common electrodes 5, and the common electrodes correspond to the position of the touch sensing electrodes 4 on the color filter substrate 10. Upon touch driving signals (Tx) being applied on the touch driving electrodes 6, the touch sensing electrodes 4 receive touch sensing signals (Rx), and then by calculation of variation of capacitance formed by the touch sensing electrodes 4 and the touch driving electrodes 6 before and after the touch operation by a finger, it is determined whether a touch occurs or not, so as to realize a touch function. In addition, a common electrode signal (Vcom) is applied on the common electrodes 5 to realize display.